In the midst of a presidential election campaign that pits a wealthy Republican businessman against a self-proclaimed warrior for the middle class, Americans are talking a lot these days about “class.” Many credit the Occupy Wall Street movement with making “class warfare”—which, in its contemporary use, is really about tax policy—a driving issue in 2012. Karl Marx and Friedrich Engels’ original idea of class struggle emerged with the creation of a class of factory wage earners during the Industrial Revolution.